As described more fully in NIS+ Authorization Classes, NIS+ access rights are assigned on a class basis.
There are four different NIS+ classes:
Owner. The owner class is a single NIS+ principal. By default, an object's owner is the principal that created the object. However, an object's owner can transfer ownership to another principal who then becomes the new owner.
Group. The group class is a collection of one or more NIS+ principals. An NIS+ object can have only one NIS+ group.
World. The world class contains all NIS+ principals that are authenticated by NIS+ (in other words, everyone in the owner and group class, plus everyone else who presents a valid DES credential).
Nobody. The nobody class is composed of anyone who is not properly authenticated (in other words, anyone who does not present a valid DES credential).